Allergan will pay $60 million up front to acquire RetroSense Therapeutics, which is developing gene therapies to restore sight in people with eye diseases. With the deal, Allergan gains access to RST-001, a gene therapy being tested in a Phase I/II study against retinitis pigmentosa, a rare disease marked by peripheral vision loss, night vision challenges, and eventual blindness. RST-001 delivers a gene called channelrhodopsin-2 that may allow new photosensors to be created in retinal ganglion cells.